1. Field of the Invention.
This invention relates to underarm and forearm crutches and such other tubular construction type hospital and patient appliances and equipment such as canes, walkers and commodes.
2. Description of the Prior Art.
Adjustable crutches embodying tubular construction are, of course, in common use. These crutches are extensible and contractible substantially along their longitudinal axes to either increase or decrease their length (height) in relation to the requirements of the individual users. In some cases, the handgrip and arm support are substantially centered relative to the longitudinal axis of the crutch. Illustrative are Murcott U.S. Pat. Nos. 3,133,551 and 3,157,187. In other cases, the handgrip and arm support are both offset from said longitudinal axis, forward thereof.
In the case of the Murcott patents, the centered relationship of the handgrip and arm support to the longitudinal axis of the crutch prevents the user from holding the handgrip in a comfortable, centered position. In consequence, the user tends to grasp the outer end of the handgrip, and this displaces the thrust line substantially forwardly of the longitudinal axis of the crutch, resulting in an excessive forward rotational bias which unbalances the crutch and fatigues the user. A similar condition obtains in the case of the crutches wherein both the handgrip and arm support are disposed forwardly of the longitudinal axis of the crutch. In such case, an excessive forward rotational bias develops, producing an unstable and fatiguing crutch design.
Commonly used on these adjustable crutches of the prior art are spring-urged lock buttons which lock the relatively movable parts together. These lock buttons do not, however, apply a spring load between the relatively movable parts, and since there is sufficient clearance for actuation of the lock buttons, the movable parts are not confined against relative vibratory movement and the like. This is true not only of adjustable crutches but also various other patient and hospital appliances and equipment made of tubular construction such as canes, walkers and commodes.